By most accounts, the fancier the setting the less impressive the cooking in Montreal Chinese restaurants. That said, some of the usual dim sum spots (Kam Fung, Ruby Rouge, maybe Tong Por) seem to do their share of wedding banquets and the like, and might be worth a shot for a relatively elaborate dinner. I don't have any recent non-dim sum experience with them, but was pleasantly surprised by dinner at Kam Fung a couple of years ago.

Shows how long it's been since I set foot there in the evening. Last time, I saw a fairly fancy seafood-oriented Cantonese menu (but stuck with the small a la carte dim sum menu). The time before, I was turned away because they were hosting a large formal banquet. But that was a couple of years ago...

I haven't been to Chez Chine in a very long time, and only for dim sum. I'd be curious to hear any recent reports.

I don't know if it would meet your definition of "fancy" but Restaurant Tao on Victoria in Westmount is a cut above in terms of decor, and the food is excellent. And it's even quite reasonably priced, to boot! Can't go wrong.

374 Victoria, just south of Sherbrooke 514-369-1332

Also.... I had my wedding reception at Cités d'Asie on Drummond downtown (below Ste-Catherine), near the Hotel Europa, and it definitely qualifies as at least semi-fancy, with very good Chinese (& sushi!):

i went recently to l'orchidée de chine - it was very good. there's also piment rouge downtown (opening a new location on decarie i believe). there's also gourmet de l'orient on bernard which isnt at the same level as the other two.

I really like Soy on St. Laurent. It is tasty, somewhat gourmet place with old standards such as General Tso's chicken, as well as more unique dishes. I have been going for YEARS and have never been disappointed.